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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 510 · 40 questions
TalentJR

The fast method (Round up, then fix): Round the number ending in 7, 8 or 9 up to the next ten: 39 → 40. Add the round number. Take away the extra you added (here 1).

NameDateTime takenScore ___ / 40
  1. 1.39 + 79 =
  2. 2.41 + 59 =
  3. 3.159 + 19 =
  4. 4.79 + 97 =
  5. 5.134 + 37 =
  6. 6.252 + 28 =
  7. 7.47 + 57 =
  8. 8.135 + 39 =
  9. 9.367 + 28 =
  10. 10.308 + 58 =
  11. 11.499 + 98 =
  12. 12.326 + 67 =
  13. 13.497 + 67 =
  14. 14.483 + 19 =
  15. 15.251 + 29 =
  16. 16.345 + 19 =
  17. 17.222 + 78 =
  18. 18.168 + 17 =
  19. 19.158 + 99 =
  20. 20.164 + 67 =
  21. 21.460 + 47 =
  22. 22.424 + 47 =
  23. 23.448 + 47 =
  24. 24.81 + 49 =
  25. 25.145 + 57 =
  26. 26.47 + 38 =
  27. 27.49 + 87 =
  28. 28.157 + 77 =
  29. 29.207 + 98 =
  30. 30.485 + 17 =
  31. 31.76 + 28 =
  32. 32.222 + 99 =
  33. 33.128 + 18 =
  34. 34.231 + 18 =
  35. 35.184 + 48 =
  36. 36.141 + 27 =
  37. 37.38 + 79 =
  38. 38.414 + 58 =
  39. 39.47 + 39 =
  40. 40.162 + 58 =

Answer key

  1. 118
  2. 100
  3. 178
  4. 176
  5. 171
  6. 280
  7. 104
  8. 174
  9. 395
  10. 366
  11. 597
  12. 393
  13. 564
  14. 502
  15. 280
  16. 364
  17. 300
  18. 185
  19. 257
  20. 231
  21. 507
  22. 471
  23. 495
  24. 130
  25. 202
  26. 85
  27. 136
  28. 234
  29. 305
  30. 502
  31. 104
  32. 321
  33. 146
  34. 249
  35. 232
  36. 168
  37. 117
  38. 472
  39. 86
  40. 220

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